Ethylene is a well known fruit ripening agent (Kays, S. and Beaudry, R. Acta Horticulturae 201: 77-115 (1987)). It has been widely used in gas form for post-harvest fruit ripening. Ethylene-containing conditioning rooms are used for ripening fruit and vegetables in bulk.
As well as ethylene per se, a large number of ethylene releasing compounds have also been used in ripening processes (Kays, S. and Beaudry supra.). These ethylene releasing compounds generally include a haloethyl group attached to a sulphur, phosphorus, or silicon atom. Their operation may be pH dependent and toxic breakdown products may be produced when used. Such compounds are primarily employed for pre-harvest plant conditioning applications.
Packaging and devices useful in post harvest fruit ripening are also known. For example, U.S. Pat. No. 3,069,274 describes a foam protector for fruit, impregnated with ethylene halides such as ethylene dichloride for fruit ripening. The use of ethylene halides in packaging is contraindicated where they produce irritating vapours that can blister skin and cause serious pulmonary damage, corneal clouding, and liver and kidney damage to people.
U.S. Pat. No. 5,525,130 describes a label device consisting of a two compartment capsule. The compartments are separated by a rupturable membrane and contain compositions that when combined release ethylene. For example, (2-chloroethyl)phosphoric acid and a base. The device is expensive and the compartment components are known skin and eye irritants.
Capsules containing ethylene gas for fruit ripening are also described in Ma et al., Journal of Fruit Quality: 23 (200) 245-259. These are impractical, large volume, plugged capsules which require plug or cap removal to allow ethylene release in packaging. Moreover, gas release is relatively rapid and non-linear.
Accordingly, there is a need for an ethylene release device that is capable of releasing ethylene without production of undesirable products. There is also a need for an ethylene release device that is of a size and type suited to inclusion in packaging. There is also a need for an ethylene release device that can appropriately control the desired rate of release of ethylene.
It is therefore an object of this invention to provide a fluid release device and related methods suitable for use in conditioning plant material which addresses at least one of the abovementioned limitations, or which may at least provides the public with a useful choice.
It may also be an object of this invention to provide a fluid release device that addresses at least some of the abovementioned limitations or which may at least provide the public with a useful choice.
Accordingly the present invention may consist in a fluid flow control valve, suitable for controlling the flow rate of fluid to the surrounding environment from a fluid storage reservoir that includes a fluid outflow passage for fluid that is at a higher pressure inside of said reservoir than the surrounding environment, said fluid flow control valve comprising:
an elastic fluid permeable membrane to control the flow of fluid through said passage, said membrane comprising
an absorption surface to absorb a fluid from the reservoir into said membrane, and
a desorption surface to desorb a fluid from said membrane to the surrounding environment;
wherein said membrane is subjected to pressure proportional to the pressure differential between the reservoir and the surrounding environment, to vary its characteristics by virtue of its elastic nature to thereby vary the effective fluid flow path between the reservoir and the surrounding environment.
Preferably the membrane is configured to passively transition between:
a more pressurised condition where a pressure is applied by the fluid in the reservoir to the membrane to bias the membrane against a flow path restrictor in a manner to define an effective fluid flow path through said membrane that is of greater resistance to the flow of fluid from said reservoir; and
a less pressurised condition where a reduced pressure is applied by the fluid in the reservoir to the membrane to bias the membrane against a flow path restrictor in a manner define an effective fluid flow path through said membrane that is of a of lower resistance to the flow of fluid from said reservoir.
Preferably the pressure of the fluid in the reservoir may communicate with said membrane via a piston having its displacement controlled by the pressure differential between the reservoir and the surrounding environment.
Preferably the effective fluid flow path is defined by the surface area of the membrane available for the absorption of fluid from the fluid reservoir and/or the surface area of the membrane available for the desorption of fluid to the surrounding environment.
Preferably at least one of the absorptive surface area and desorptive surface area of the membrane increases proportionate to a decreased pressure applied to the membrane by the fluid in said reservoir as the fluid in the reservoir depletes.
Preferably the fluid permeable membrane is a gas permeable deformable elastomer.
Preferably it is in the shape of an O-ring.
Preferably the fluid permeable membrane may comprise a plurality of gas permeable deformable elastomeric components, such as O-rings.
Preferably the device further comprises:
a flow path restrictor to define the effective fluid flow path and that includes an orifice configured to offer a variable effective size, wherein variation in effective size occurs as a result of an interaction between the membrane and the flow path restrictor, and
wherein the fluid in the reservoir is in operative contact with said membrane and directly communicates the pressure of the fluid to said membrane proportionate to the pressure differential across said membrane.
Preferably the flow path restrictor includes a recess in communication with an edge of said orifice.
Preferably the recess may comprise a shaped portion of at least part of an edge of said orifice.
Preferably in use, a biasing of the membrane occurs to bring the desorptive surface of said membrane into contact with at least one of said flow path restrictor to reduce the effective fluid flow path defined by said orifice.
Preferably the area of the desorptive surface of the membrane in contact with at least one of the flow path restrictors is inversely proportionate to the pressure differential between the fluid in the reservoir and the surrounding environment.
Preferably the membrane is sensitive to the pressure applied to the membrane to vary the permeability of fluid through the membrane to thereby at least in part control the effective fluid flow path characteristics.
Preferably the membrane is selected from the group comprising elastomeric polymers such as silicone, synthetic hydrocarbons and natural rubber and combinations thereof.
Preferably the fluid is a gas.
Preferably the gas is ethylene, propylene, methyl cyclopropene, pyrethrin/sythetic pyrethroids, ethylene oxide, methyl bromide, carbon dioxide, or sulphur dioxide or any similar gas or gas mixture containing one of these gasses as an ingredient.
Preferably the gas may have anaesthetics, propulsion, aroma, flavour, fragrance, pheromone, fumigant, pesticide and/or corrosive properties.
Preferably the fluid flow control valve provides a substantially linear fluid flow rate profile over a substantial portion of time of discharge of fluid from said reservoir.
Preferably the fluid flow control valve provides a final rapid release of residual fluid in said reservoir at a predetermined pressure differential.
In a further aspect the present invention consists in a fluid release device that comprises a reservoir with which there is associated a fluid flow control valve as herein before described.
In still a further aspect the present invention consists in a method for conditioning plant material comprising the steps of:
containing a plant material in an environment that is at least partially gas-tight;
exposing the plant material to fluid released from a fluid release device as herein before described to condition the plant material.
Preferably the at least partially gas tight environment comprises an outer cover, desirably said cover serves to substantially limit the mass transport of gases to permit an accumulation of ethylene gas internally while remaining sufficiently permeable to respiratory gases such as carbon dioxide and oxygen to maintain a beneficial environment for fruit to be receptive to ethylene.
In still a further aspect the present invention consists in a method for conditioning plant material comprising the step of exposing the plant material to a concentration of ethylene gas between about 1 ppm to about 250 ppm for time between around 0.5 day to 14 days.
Preferably, in the case of said plant material being pears or bananas, the range is maintained between 100 ppm and 200 ppm for 2 to 5 days.
Preferably the method is performed during the transit of said plant material between two locations.
In still a further aspect the present invention consists in a fluid release valve comprising a fluid permeable membrane provided between a fluid storage reservoir and the surrounding environment, said membrane configured to control at least one of:
the rate of absorption of the fluid onto the surface of the membrane;
the rate of permeation of the fluid through the membrane; and
the rate of desorption of the fluid from the surface of the membrane to the environment.
In yet a further aspect the present invention consists in a fluid release valve suitable for regulating a flow of fluid from a fluid reservoir, said fluid release valve comprising a body member including:
(i) an inlet, and
(ii) an outlet in fluid communication with the inlet via a flow passage;
(iii) a fluid permeable membrane extending across the flow passage to restrict the flow of fluid between said inlet and outlet; and
(iv) an impervious flow path restrictor;
wherein the flow path restrictor and the membrane are configured and adapted operationally to interact with each other to allow the flow of fluid along the flow path as a function of the quantity of fluid in the fluid reservoir.
Preferably the flow rate of fluid along the flow path may be controlled by the interaction of the flow path restrictor and the membrane to be substantially constant.
Preferably it includes a closure member for closing the flow passage so that no fluid may flow through it.
Preferably it includes the fluid reservoir.
Preferably the flow path restrictor is displaceable between
a restricted barrier position in which it is engaged more with said membrane whereby the fluid flow passage is more restricted, and
a less restricted barrier position in which it is engaged less with said membrane whereby the fluid flow passage is less restricted.
Preferably the membrane is displaceable between
a restricted barrier position in which it engages more with said flow path restrictor whereby the fluid passage is more restricted, and
a less restricted barrier position in which it is engaged less with said flow path restrictor whereby the fluid flow passage is less restricted.
Preferably the fluid reservoir is pressurised in relation the surrounding environment and the membrane and flow path restrictor interact with each other to vary the effective flow path through said passage by virtue of the pressurised fluid.
Preferably the interaction of the flow path restrictor and the membrane is such that the flow path is more restricted when the pressure in the fluid reservoir is high, and the flow path is less restricted when the pressure in the fluid reservoir is relatively lower.
Preferably the flow rate of fluid along the flow path is controlled by the interaction of the flow path restrictor and the membrane to be substantially constant over time until the quantity of fluid in the fluid reservoir has reached a predetermined lower threshold, after which the flow path is not restricted by the interaction of the membrane and/or the flow path restrictor, and an uninterrupted passage is established between any remaining fluid in the reservoir and the surrounding environment.
Preferably the flow path restrictor is located adjacent the membrane to allow a variable amount of contact therebetween to vary the permeation of fluid through the membrane.
Preferably the flow path restrictor is disposed proximal more the inlet of the passage relative the membrane, said flow path restrictor presented to interact with said membrane to influence the absorbtion of fluid into the membrane.
Preferably the flow path restrictor is disposed proximal more the outlet of the passage relative the membrane to interact with said membrane to influence the desorbtion of fluid from said membrane.
Preferably the flow path restrictor and the membrane can move relative to each other and come into variable degree of contact to deform the membrane so as to restrict permeation of the fluid through the membrane.
Preferably the membrane is composed of an elastically resilient material.
Preferably the membrane is composed of material selected from the group of elastomeric polymers such as silicone, synthetic hydrocarbons and natural rubber and any combinations thereof.
Preferably the flow path restrictor is of a non permeable material.
Preferably the flow path restrictor is composed of an inelastically resilient material.
Preferably the fluid in the fluid reservoir is a gas.
Preferably the gas is selected from of ethylene, propylene, methyl, cyclopropene, pyrethin or synthetic pyrethroids, ethylene oxide methyl bromide, pheromones, fumigants, pesticides, carbon dioxide, sulphur dioxide or any similar gas or gas mixture containing one of these gases as an ingredient.
Preferably the gas may include anaesthetic, propulsion, fragrance, aroma, flavour, and corrosive properties.
Preferably the membrane is in the form of a planar film.
Preferably, the membrane is a hollow sheath.
Preferably the flow path restrictor is defined by a body having a cavity that is in fluid communication with the surrounding environment and with at least one opening to the cavity that is in fluid communication with said fluid in said reservoir via said membrane.
Preferably the body includes a hollow cylindrical portion.
Preferably the hollow sheath is configured and dimensioned to fit snugly around at least part of the cylindrical portion and fluid pressure can act on the sheath to bias it against the hollow body.
Preferably formed at the cylindrical region is at least one annular channel into which the membrane, under pressure from said fluid may be forced yet be resiliently biased in a direction out of the channel.
Preferably the cylindrical region includes a plurality of annular channels.
Preferably the fluid pressure can act against the sheath's elasticity to encourage the sheath to
(a) conform to the channel or channels at higher reservoir fluid pressures, thereby restricting the flow of fluid through the apertures in the hollow tube; and
(b) retract at least partially from contact with the channel or channels at lower pressures thereby reducing the restriction on the fluid flow.
Preferably the body includes a pressure release passage formed into an outer surface of the body and with which said sleeve can interact to become compliant therewith under higher fluid pressure thereby closing said passage and which can enable unrestricted fluid communication of the fluid reservoir with the surrounding environment at a predetermined lower fluid threshold pressure.
Preferably the flow path restrictor may include a cylindrical piston movable within a cylindrical bore in the body member.
Preferably comprises an annular ring.
Preferably the annular ring is of a cross sectional shape which is circular, triangular, square, polygonal, or any other shape.
Preferably a piston is configured to press against the annular ring under pressure of the pressurised fluid.
Preferably the body member includes an inner annular lip against which the annular ring may be pushed by the piston.
Preferably the piston is configured to press the annular ring against the annular lip under pressure of the pressurised fluid, thereby deforming the annular ring.
Preferably the increased deformation of the annular ring at high pressure will restrict the flow of fluid through the permeable annular ring, and the decreased deformation of the annular ring at lower pressures allows a more unrestricted flow of fluid through the permeable annular ring.
Preferably the fluid release valve includes a plurality of annular rings.
Preferably each of the plurality of annular rings is spaced apart by impermeable spacing members.
Preferably the annular ring may be an O-ring.
Preferably he fluid release valve, in use, provides a substantially linear fluid flow profile over a substantial portion of time of operation of the device.
In a further aspect the present invention consists in a method for conditioning plant material comprising the steps of:
providing a fluid release valve as herein before described that is associated with a pressurised fluid reservoir in an environment that is at least partially fluid-tight and that contains plant material;
exposing the plant material to fluid from the fluid release valve over a time period.
Preferably the time period is between 0.5 to 14 days.
Preferably the time period is 5 days.
Preferably the fluid released by the fluid release valve is ethylene.
Preferably the at least partially fluid-tight environment comprises a covered container that restricts the dispersion of the gas to permit an accumulation of ethylene gas internally while remaining sufficiently vented to the air so as to maintain a beneficial environment for fruit to be receptive to ethylene.
Preferably the plant material is retained in the environment with a concentration of ethylene gas of between about 1 ppm to about 250 ppm for a time period of between half a day to 7 days.
Preferably the plant material is retained in the environment with a concentration of ethylene gas of between about 100 ppm and 200 ppm for 2 to 5 days.
In yet a further aspect the present invention consists in a method of conditioning plant material in transit comprising the steps of
at least partially enclosing the plant material in an isolated environment;
loading the plant material onto a transportation means;
providing a fluid release valve as herein before described that is associated with a pressurised fluid reservoir, within the cover;
retaining the plant material in the isolated environment that includes fluid released by the fluid release valve from said reservoir over a period of time.
Preferably the plant material is a fruit.
In still a further aspect the present invention consists in a gas release device comprising or including
a reservoir of pressurised gas to be released,
a passageway from said reservoir to an outlet,
an elastic gas permeable membrane in the passageway and/or at the outlet that allows gas release only via the membrane to, or from, the outlet, and
a gas impermeable member in said passageway that includes a gas permeable member interface positioned to contact said gas permeable membrane,
wherein displacement of the gas permeable membrane is responsive to the pressure of the gas in the reservoir such that there is a greater interfacial contact between the gas impermeable member and said gas permeable membrane at a higher gas pressure than at lower pressure to thereby vary the exposed cross sectional area of the permeable membrane available to the flow in an inverse relationship to pressure.
Preferably the gas permeable membrane is elastic.
Preferably the gas impermeable member is rigid.
Preferably the gas permeable membrane elasticity at the interface is to reduce the interfacial contact with said gas impermeable member as the pressure decreases.
Preferably the gas permeable membrane is responsive in a progressive manner.
In still a further aspect the present invention consists in a method of packaging fruit comprising, placing in a container that holds or is to hold fruit, a cartridge containing a fixed quantity of ethylene that can be activated to release ethylene at a constant flow rate over a period of time and activating the cartridge and shipping the container with fruit contained therein to a destination.
In yet a further aspect the present invention consist in a container containing fruit that includes a cartridge containing a fixed quantity of ethylene that can be activated to release ethylene at a constant flow rate over a period of time and activating the cartridge and shipping the container with fruit contained therein to a destination.
In even a further aspect the present invention consists in a self contained gas release device that can release a gas at a constant flow rate over a period of time, said device comprising;
a pressure vessel that contains a gas to be discharged there from,
a valve for said pressure vessel to control the discharge of gas from said pressure vessel, said valve comprising
(a) a body that defines (i) an aperture for discharging gas to pass through to the environment surrounding said device and (ii) a control surface
(b) an elastic gas permeable membrane interposing direct gas flow from said pressure vessel to said aperture so that gas must permeate through said membrane in order to discharge from said pressure vessel, said membrane located adjacent said control surface to, at lower gas pressure of said gas, form a passage between said control surface and said aperture that is of a greater size than at higher gas pressure where said membrane is more compliant to the shape of the control surface by virtue of a higher gas pressure biasing the membrane against said control surface.
In a further aspect the present invention consists in a self contained gas release device that can release a gas at a constant flow rate over a certain period of time, said device comprising;
a pressure vessel that contains a gas to be discharged there from,
a valve for said pressure vessel to control the discharge of gas from said pressure vessel, said valve comprising
(a) a body that includes a cylindrical body portion that has at least one circumferential groove formed into it, and where, within said groove there is at least one aperture that makes a fluid connection between the groove with the environment surrounding said device for discharging gas to pass through
(b) an elastic gas permeable membrane that is located over said groove to interpose direct gas flow from said pressure vessel to said aperture so that gas must permeate through said membrane in order to discharge from said pressure vessel, said groove being of a profile to allow variable compliance of the membrane against at least part of the groove as a result of variation in pressure of the gas acting on the membrane wherein as the gas discharges and the gas pressure in the vessel decreases, the membrane releases from said groove to make available more surface area for the desorbtion of gas permeating through said membrane to increase the effective flow path for gas, and wherein by virtue of the decrease in pressure the gas discharge rate can remain substantially constant over a period of time.
Preferably the period of time includes time between 0.5 to 7 days.
In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art.
As used herein the term “and/or” means “and” or “or”, or both.
As used herein “(s)” following a noun means the plural and/or singular forms of the noun.
The term “comprising” as used in this specification means “consisting at least in part of”. When interpreting statements in this specification which include that term, the features prefaced by that term in each statement all need to be present but other features can also be present. Related terms such as “comprise” and “comprised” are to be interpreted in the same manner.
It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7).
This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.